In the acute phase of cerebral circulatory disturbance, the principal object has heretofore been put in the treatment of which the primary purpose is life-saving, and substantially no treatment for relieving sequelae has been effected. On the other hand, in the chronic phase, various cerebral circulation and metabolism ameliorants have been used. However, since the symptomatology has already been fixed, an improvement of neurological symptoms and activities of daily living which improvement has been most desired has not been observed with these cerebral circulation and metabolism ameliorants.
Therefore, it has now become considered that an adequate treatment in the acute phase can relieve the sequelae, particularly neurological sequelae.
Accordingly, there has been desired a development of a compound which has a brain-protecting action by which cell death in the cerebral ischemia is depressed, is weak in such central depressant action as to make the whole body control of patient difficult, and is further chemically stable.